Let’s say that your email address is ‘GeorgeBush@gmail.com’, basically everything sent to any of the following email addresses will be forwarded to your primary email.
And that’s not all, you can place as many dots as you want, it can be even something like ‘G.e.o.r.g.e.B.email@example.com’ and you’ll still get it on ‘GeorgeBush@gmail.com’
Additionally, I just also found out that you can embed random text to your email ID using ‘+’ sign. That is to say ‘GeorgeBushfirstname.lastname@example.org’ can be used as your email address, as well.
Ok I got it. Now what ?
1. One email for every purpose
Instead of using different email addresses for various purposes (work, school, friends, etc.) you can use different variations of your Gmail and filter incoming mails by ’sent to’ address. For instance, all incoming mail sent to ‘Name.Surname@gmail.com’ can be put to folder ‘work’, messages sent to ‘NameSurname@gmail.com’ can be put to ‘friends’, ‘N.ameSurname@gmail.com’ can be used for newsletters, and so on.
2. Track/Block spammers
When signing up for some website, say thatwebsite.com, you can add thatwebsite to your Gmail user ID (eg. GeorgeBushemail@example.com). This way you can block your subscription whenever you want and even identify those websites that distribute your email address to spammers.
And this is what Google explain
Sometimes you may receive a message intended for someone whose address resembles yours but has a different number or placement of dots. For example, your address might be firstname.lastname@example.org, but the message was sent to a Homer.J.Simpson@gmail.com. What’s going on?
Gmail allows only one registration for any given username. Once you sign up for a particular username, any dot or capitalization variations are made permanently unavailable for new registration. If you created email@example.com, no one can ever register firstname.lastname@example.org, or Your.email@example.com. Furthermore, because Gmail doesn’t recognize dots as characters within usernames, adding or removing dots from a Gmail address won’t change the actual destination address. Messages sent to firstname.lastname@example.org, email@example.com, and firstname.lastname@example.org are all delivered to your inbox, and only yours.
If you’re email@example.com, no one owns Homer.J.Simpson@gmail.com, except for you. Sending mail to Homer.J.Simpson@gmail.com is the same as sending mail to firstname.lastname@example.org, or even HOMERJSIMPSON@GMAIL.COM. If you’re getting mail addressed to Homer.J.Simpson@gmail.com, most likely someone was trying to send a message to Homer.J.Sampson@gmail.com, or Homer.J.Simpson1@gmail.com, and made a mistake. You might even get messages from mailing lists or website registrations because the intended recipient accidentally provided the wrong email address. In these cases, we suggest contacting the original sender or website when possible to alert them to the mistake.
For security reasons, when you log in to Gmail, you must enter any dots that were originally defined as part of your username.
Note: Google Apps recognizes dots. If you’d like to receive mail with a dot in your username, please ask your domain administrator to add the desired username as a nickname.
Credit : Various Source